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At least 145 records · Page 8Linked to original sources
PubMed2002

Novel clade of Rickettsia spp. from leeches.

Intracellular rickettsia-like structures were found in the tissues of a glossiphoniid leech, Torix tagoi, by transmission electron microscopy. Diagnostic PCR analysis using specific primers suggested that of the nine glossiphoniid species examined, two species, T. tagoi and Hemicrepsis marginata, harbored bacteria of the genus Rickettsia. A 1.5-kb eubacterial 16S rRNA gene segment obtained from each of these species was amplified by PCR, cloned, and sequenced. Phylogenetic analysis of the 16S rRNA gene demonstrated that the Rickettsia species found in the leeches constituted a novel clade that is distinct from the clade of arthropod-associated Rickettsia species. In natural populations, 97.7% (43 of 44) of T. tagoi leeches and 100% (9 of 9) of H. marginata leeches carried Rickettsia, suggesting that infection with Rickettsia is prevalent in these leeches. This is the first report of Rickettsia found in annelids.

Animals↗
PubMed1989

Aeromonas hydrophila infection associated with the use of medicinal leeches.

The use of medicinal leeches (Hiruda medicinalis) is becoming more common after plastic surgery to control venous congestion of skin grafts. We describe a patient with Aeromonas hydrophila infection whose graft was treated with medicinal leeches. The infection required systemic antibiotic therapy. A. hydrophila is the predominant bacterial flora in the gut of the leech, where it plays an essential role for the animal in the digestion of blood. The potential for A. hydrophila wound infection, and appropriate antibiotic prophylaxis of the leech or patient, should be considered when medicinal leeches are used.

Aeromonas↗
PubMed1987

On the termination of ingestive behaviour by the medicinal leech.

Hungry leeches, Hirudo medicinalis, ingest blood meals averaging 890% of their mass in 29 min. Ingestion is terminated as a result of distension of the body: experimentally distending leeches as they feed causes an immediate cessation of ingestion and inhibits any subsequent biting behaviour; if distension is circumvented by various experimental procedures, leech ingestive periods are prolonged significantly. Ingestion is not terminated as a result of fatigue, chemical cues or mass change. Distension also underlies satiation, for removing blood from the crops of recently fed leeches qualitatively alters their satiated behaviour to biting. Biting is not a defensive reaction to injury. In rostral ganglia, impulses of the serotonergic Retzius (RZ) and LL neurones evoke the physiological components of ingestion. Localized warming of the prostomial lip induces impulses in these large effector neurones. Distending the body wall tonically hyperpolarizes the RZ and LL cells. This inhibitory response to distension is conducted from the mid-body to the anterior neurones via the ventral nerve cord. Distensive inhibition antagonizes the synaptic excitation evoked in RZ and LL neurones by thermal stimulation. Thus, a stimulus which evokes feeding synaptically excites 5-HT neurones and a stimulus which terminates ingestion inhibits them. The integration of these inputs controls the expression of leech feeding behaviour and these connections match precisely a model proposed to regulate the ingestive behaviour of blowflies.

Animals↗
PubMed1992

Influence of substrate on retraction of neurites following electrical activity of leech Retzius cells in culture.

1. The aim of these experiments was to determine how electrical stimulation of identified neurones in culture influences their growth on defined substrates. Single Retzius cells isolated from the central nervous system (CNS) of the leech were plated in culture dishes coated with the plant lectin Concanavalin A or with extracellular matrix extract containing leech laminin to promote neurite outgrowth. Stimuli were applied by a fine tungsten microelectrode placed close to the cell surface. The efficacy of electrical stimulation was checked occasionally by recording intracellularly with a microelectrode. 2. After the period of stimulation had ended, there was a short delay before neurones plated on leech laminin retracted their neurites. Of 112 neurones, only 11 failed to respond to stimulation. Neurite retraction in each cell was non-uniform, some processes retracting while others did not. After having retracted, most neurites subsequently showed clear regrowth. The degree of retraction depended on the duration of the stimulus train: whereas a few minutes was sufficient to produce observable effects, prolonged periods of stimulation caused more extensive retraction. Trains of impulses at 4 s-1 were equally effective when they were delivered in intermittent bursts or continuously. 3. The time in relation to growth at which stimuli were applied was of critical importance. Neurones stimulated during the phase of rapid outgrowth on leech laminin did not retract their neurites, which continued to elongate during and after stimulation. Neurones that had not retracted during the early phase were stimulated again later, when extension and outgrowth of neurites had ceased or slowed. At this stage stimulation was followed by retraction and subsequent regrowth. 4. Retzius cells plated on a substrate of Concanavalin A instead of leech laminin failed to show any retraction after stimulation. 5. To investigate the possible role of Ca2+, cells were grown with raised concentrations of Mg2+ in the bathing fluid. Raised [Mg2+] did not influence the rate or the extent of neurite outgrowth. It reduced, but did not block, the effects of electrical stimulation. Earlier experiments have shown that growth on Concanavalin A occurs without obvious Ca2+ entry following stimulation. Together with the present experiments, the results suggest that Ca2+ entry following impulses in cells grown on laminin is responsible for the massive retraction.

Action Potentials↗
PubMed1996

Mapping motor neurone activity to overt behaviour in the leech: internal pressures produced during locomotion.

Several behaviour patterns have been studied in the leech at both the kinematic and neuronal levels. However, very little is known about how patterns of motor neurone activity map to actual movements. Internal pressure is an essential biomechanical property in this process, being responsible for producing the rigidity and posture that allow the directed delivery of forces produced by muscle contraction. To obtain a better understanding of the biomechanical processes involved in movement of the leech, we have measured the internal pressure of the animal by placing catheters through the body wall and into the gut of intact animals showing normal patterns of behaviour. Each type of behaviour had a characteristic pressure waveform. The elongation phase of crawling produced a rapid increase in pressure that peaked when midbody segments were maximally elongated. The pressure produced during the contraction phase of crawling depended on the type of crawl, only inchworm crawling producing a second peak. Whole-body shortening in response to a head poke also produced a pressure peak, but it had a faster rise time. Swimming produced the largest pressure, which was marked by a large sustained increase that fluctuated phasically with undulations of the body. Dual pressure recordings using two catheters demonstrated that pressure was not uniform along the length of the leech, indicating that the body cavity is functionally compartmentalised. Injecting fluid into the gut via a recording catheter allowed us to determine the effects of increasing internal volume on pressure. In line with previous predictions made using an abstract biomechanical model of the leech hydroskeleton, we found that an increase in the volume caused a reduction in the pressure. We are in the process of constructing a more realistic biomechanical model of the leech, based on actual data reported elsewhere. The results in this paper will provide key tests for refining these models.

Animals↗
PubMed1990

Aeromonas, acclimation, and penicillin as complications when leeches are applied to skin flaps in rabbits.

The medicinal leech, Hirudo medicinalis, has been recognized by plastic surgeons for its ability to reduce congestion and improve blood flow in grafted skin flaps by withdrawing excess blood. The leech's ability to digest blood is due to the presence of Aeromonas hydrophila in the gut of the leech. In this report we describe the occurrence of Aeromonas hydrophila septicaemia in rabbits used in a study to evaluate the efficacy of the medicinal leech on abdominal skin flap survival. In New Zealand White rabbits, twin 5 x 10 cm abdominal skin flaps were prepared and the epigastric vein was ligated to produce a model of venous congested skin. After 12 hours, a leech was applied to one of the congested abdominal flaps and skin survivability was assessed and compared with the unleeched flap. Five rabbits died acutely approximately 24 hours post-operatively. Gross necropsy, bacteriology and histopathology findings indicated that A. hydrophila was the causative agent of the septicaemia-toxaemia syndrome with an associated pneumonia and typhlitis. Review of the management and the experimental surgery protocol suggested that the two major disposing factors of Aeromonas septicaemia in these rabbits were stress and excessive prophylactic administration of penicillin.

Aeromonas↗
PubMed1988

The medicinal leech. A page from the annelids of internal medicine.

Leeches have been used in health care since ancient times by physician and layman alike. As just one of several methods of bloodletting, the leech became the focus of a science that included such subjects as indications, modes of attachment, complications, and relative contraindications. The popularity of leeching has varied immensely over the years. In the 19th century, this annelid saw its numbers decimated because of protean medicinal indications. The leech lost its hold on the practice of medicine in the early 20th century. Recently, the use of leeches has resurged in both the lay and the scientific communities.

Animals↗
PubMed1988

[A case report of nasal infestation by the leech, Dinobdella ferox].

A 55-year-old man in Okagaki Town, Fukuoka Prefecture, pulled a nasal leech from his nostril in July 1987, after suffering from nosebleed, copious running snivels as well as unpleasant foreign body sensation in the nasal cavity. Except for nasal septum deviation, no abnormality in the ears and mouth cavity nor bleeding, ulcerous and erosive changes in the nasal cavity were found. The formalin-fixed specimen of the leech was nearly black with no definite stripes or spots, and measured 3.5 cm in length and 1.2 cm in width. Because of these and the following characteristics, viz. 1) auricles on the posterior segment were absent, 2) five pairs of eyes were present in the anterior segments with the eye pairs 3 and 4 separated by an annulus, and 3) teeth were not observed, this specimen was identified as Dinobdella ferox. This nasal leech is found widely in Southeast Asia. In Japan, some human cases of its infestation have also been reported, mainly from southern Kyushu. The leech seemed to have entered the nasal passage of the present case from a stream at a hot spring in northern Kyushu. Attention should be given to nasal leech infestation especially now that many people in Japan are eager to visit isolated hot spring resorts.

Animals↗
PubMed1991

Aeromonas hydrophila infections following clinical use of medicinal leeches: a review of published cases.

Ten Aeromonas hydrophila infections following postsurgical leech applications have been reported. These cases indicate that postsurgical wounds and damaged tissue can provide entry for either acute or delayed A. hydrophila infection. These infections can range from localized cellulitis to progressive myonecrosis and sepsis. These infections may occur with measurable frequency in groups of patients exposed to leeches. Based on this review, it is recommended that leeches be applied only to tissue with a reasonably certain arterial supply; that patients receive antibiotics against A. hydrophila prior to leech administration; and that consideration be given to prolonged antibiotic administration to patients discharged home with open wounds or questionably viable tissue after leech administration.

Aeromonas↗
PubMed1991

Modification of leech behavior patterns by reserpine-induced amine depletion.

A single injection of 100 micrograms reserpine into the crop of the medicinal leech, Hirudo medicinalis, reduced CNS serotonin and dopamine levels to less than 1% of control values within 3 d. High-pressure liquid chromotography- (HPLC) determined CNS serotonin and dopamine levels remained maximally depressed for approximately 1 month following reserpine injection. Subsequently, amine levels recovered slowly, but remained depressed 6 months after reserpine injection. Following reserpine treatment, glyoxylic acid-induced fluorescence or neutral red staining closely mirrored the HPLC-determined time course of amine depletion and recovery. Acute exposure of isolated ganglia to 10 microM reserpine for periods up to 6 hr produced a 20-30% reduction of serotonin and dopamine content. The threshold concentration of reserpine necessary to produce amine depletion was approximately 1 microM. We found that reserpine treatment eliminated biting behavior within 4 d following injection. Biting behavior remained depressed below control levels for approximately 4 months, but returned to control values while CNS serotonin and dopamine levels remained significantly depressed at this time. Unexpectedly, reserpine treatment increased rather than reduced the duration of stimulus-evoked swimming activity. This behavioral change was evident within 3 d and persisted for approximately 3.5 months. To rapidly restore amine levels in reserpine-treated animals, we bathed intact leeches in pond water containing serotonin, dopamine, or octopamine. We found that biting behavior was restored following reserpine treatment by bathing intact leeches in pond water containing serotonin or dopamine, but not octopamine. Also contrary to expectations, the increase in swim duration was not reversed by bath exposure to serotonin, dopamine, octopamine, or histamine. However, all swimming activity in reserpine-treated leeches was eliminated by the amine antagonist cyproheptadine. We propose that the presence of low levels of amines is critical for the expression of both biting and swimming activity in leeches. However, the minimal levels of amines necessary for the expression of these behaviors are lower for swimming than for biting.

Animals↗
PubMed1990

Conversion of recombinant hirudin to the natural form by in vitro tyrosine sulfation. Differential substrate specificities of leech and bovine tyrosylprotein sulfotransferases.

Hirudin, a tyrosine-sulfated protein secreted by the leech Hirudo medicinalis, is one of the most potent anticoagulants known. The hirudin cDNA has previously been cloned and has been expressed in yeast, but the resulting recombinant protein was found to be produced in the unsulfated form, which is known to have an at least 10 times lower affinity for thrombin than the naturally occurring tyrosine-sulfated hirudin. Here we describe the in vitro tyrosine sulfation of recombinant hirudin by leech and bovine tyrosylprotein sulfotransferase (TPST). With both enzymes, in vitro sulfation of recombinant hirudin occurred at the physiological site (Tyr-63) and rendered the protein biochemically and biologically indistinguishable from natural hirudin. However, leech TPST had an over 20-fold lower apparent Km value for recombinant hirudin than bovine TPST. Further differences in the catalytic properties of leech and bovine TPSTs were observed when synthetic peptides were tested as substrates. Moreover, a synthetic peptide corresponding to the 9 carboxyl-terminal residues of hirudin (which include Tyr-63) was sulfated by leech TPST with a similar apparent Km value as full length hirudin, indicating that structural determinants residing in the immediate vicinity of Tyr-63 are sufficient for sulfation to occur.

Adrenal Medulla↗
PubMed1990

[The effect of preparations of Hirudo medicinalis leeches on DNA methylation in the rat liver].

The effect of the salivary gland secretion and dialysable part of the homogenate of the leeches Hirudo medicinalis on the methylation of DNA in the rat liver after the intraperitoneal injection and perfusion of isolated liver has been analysed. The maximum concentration of 5-methylcytosine is observed 1 h later the injection of preparations: for the salivary gland secretion the increase is 39%, for the dialysate of leech homogenate is 28%. The 5-methylcytosine content increases on 28% after the perfusion of isolated liver with the leech saliva and after the dialysate of the leech homogenate--on 20%. No other changes in DNA content is observed. It is suggested that the DNA-methylation of the liver cells is due to the penetration of biologically active substances produced by the medical leech into the cell-targets accompanied by the forming of corresponding ligand-receptor complexes.

5-Methylcytosine↗
PubMed1988

Antithrombotic effect of preparations from the leeches Hirudo medicinalis.

Antithrombotic effect of leech salivary gland secretion was maximal after intravenous administration into rats and was slightly decreased in cases of peroral administration. Blood from leech intestinal tract and leech homogenate exhibited less distinct antithrombotic action. Effect of these preparations was maintained after peroral administration. The antithrombotic effect of the leech preparations did not depend on their antithrombic activity caused by hirudin. These leech preparations appear to elongate a period of blood plasma recalcification caused by kallikrein inhibitor as well as apparently due to their capacity to inhibit aggregation of the thrombocytes.

Administration, Oral↗
PubMedDate not supplied

[Antithrombotic effect of salivary gland secretion and other preparations from the leech Hirudo medicinalis after intravenous and peroral administration to rats].

Antithrombotic effect of leech salivary gland secretion was maximal after intravenous administration into rats and was slightly decreased in cases of peroral administration. Blood from leech intestinal tract and leech homogenate exhibited less distinct antithrombotic action. Effect of these preparations was maintained after peroral administration. The antithrombotic effect of the leech preparations did not depend on their antithrombic activity caused by hirudin. These leech preparations appear to elongate a period of blood plasma recalcification caused by kallikrein inhibitors as well as apparently due to their capacity to inhibit aggregation of the thrombocytes. Relatively low molecular mass substances, penetrating through pores of cellophan membrane during dialysis, were responsible for the antithrombotic effect of the preparations studied.

Administration, Oral↗
PubMed1987

FMRFamide-like substances in the leech. III. Biochemical characterization and physiological effects.

FMRFamide-like immunoreactivity has been previously localized to identified neurons in the CNS of the leech, Hirudo medicinalis (Kuhlman et al., 1985a). These leech antigens have been characterized biochemically by reverse-phase high-pressure liquid chromatography (HPLC) followed by radioimmunoassay (RIA). The majority of the FMRFamide-like immunoreactivity recovered by HPLC from extracts of leech nerve cords coelutes with authentic FMRFamide. We have tentatively identified this major leech peptide as authentic FMRFamide. Two neurons that control heartbeat in the leech, the HE motor and HA modulatory neurons, and their neural processes on the heart are FMRFamide-like immunoreactive (Kuhlman et al., 1985a). Single individually dissected HE and HA cells were analyzed by HPLC and RIA. Only 1 FMRFamide-like peptide was found in extracts of HA cells; this peptide was chromatographically indistinguishable from authentic FMRFamide. The FMRFamide-like peptide in HE cells could not be isolated by experimental procedures used. Most of the FMRFamide-like immunoreactivity contained within the neural processes on the heart also coeluted with authentic FMRFamide. HE motor neurons, which are believed to be cholinergic (Wallace, 1981a, b; Maranto and Calabrese, 1984a, b), were examined for their FMRFamide-like effects on the heart. The presence of curare in the bathing medium did not block the ability of FMRFamide to induce myogenic activity in heart muscle, suggesting that FMRFamide and ACh act at different receptor sites on the heart. Prolonged firing in HE cells in the presence of curare also induced myogenic activity in heart muscle. This FMRFamide-like action of the HE motor neurons may be normally masked by their cholinergic actions.

Animals↗
PubMed1997

Map turtle winter leech loads.

Adult common map turtles, Graptemys geographica (n = 243), were obtained in November 1995 from a hibernation site in the Lamoille River, Vermont. Of the 208 female turtles examined, 151 (72.6%) had at least 1 leech (Placobdella parasitica) attached and 10 of 35 males (28.6%) were similarly parasitized. Mean abundances were 1.49 (SD = 1.461, n = 208) for female turtles and 0.34 (SD = 0.591, n = 35) for males; the difference was significant (t = 4.558, df = 241, P < 0.001). Leech broods were found on 34 of 208 female turtles (16.3%) and 2 of 35 males (5.7%). One of the leeches was of record size (77.7 mm total length); another specimen measuring 64.4 mm had 153 brood-sized (x = 4.5 mm) young attached to its venter. Because of poor visibility and partial ice cover, only 7 turtles were recovered in March 1996. All of these turtles had attached leeches, and 4 turtles had broods of 9-52 young ranging in length from 4.58 to 5.78 mm. One Placobdella ornata was found in the March sample. Our results suggest that leeches of various size classes remain attached to hibernating adult map turtles throughout the winter.

Animals↗
PubMed2006

Effect of mu and kappa opioids on injury-induced microglial accumulation in leech CNS: involvement of the nitric oxide pathway.

Damage to the leech or mammalian CNS increases nitric oxide (NO) production and causes accumulation of phagocytic microglial cells at the injury site. Opioids have been postulated to modulate various parameters of the immune response. Morphine and leech morphine-like substance are shown to release NO and suppress microglial activation. Regarding the known immuno-modulatory effects of selective mu and kappa ligands, we have assessed the effect of these agents on accumulation of microglia at the site of injury in leech CNS. Leech nerve cords were dissected, crushed with fine forceps and maintained in different concentrations of opiates in culture medium for 3 h and then fixed and double stained with Hoechst 33258 and monoclonal antibody to endothelial nitric oxide synthase (NOS). Morphine and naloxone (> or =10(-3) M) but not selective mu agonist, DAMGO [d-Ala2, N-Me-Phe-Gly5(ol)-enkephalin] and antagonist, CTAP [D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2] inhibited the microglial accumulation. The effect of morphine was abrogated by pre-treatment with naloxone and also non-selective NOS inhibitor, l-NAME [N(omega)-nitro-l-arginine-methyl-ester; 10(-3) M] implying an NO-dependent and mu-mediated mechanism. These results are similar to properties of recently found mu-3 receptor in leech, which is sensitive to alkaloids but not peptides. Both selective kappa agonist, U50,488 [3,4-dichloro-N-methyl-N-(2-(1-pyrrolidinyl)cyclohexyl)-benzeneacetamide; > or =10(-3) M], and antagonist, nor-binaltorphimine (nor-BNI; > or =10(-3) M), inhibited the accumulation. The effect of nor-BNI was reversed by l-NAME. Immunohistochemistry showed decreased endothelial NOS expression in naloxone and U50,488-treated cords. Since, NO production at the injury site is hypothesized to act as a stop signal for microglias, opioid agents may exert their effect via changing of NO gradient along the cord resulting in disruption of accumulation. These results suggest an immuno-modulatory role for mu and kappa opioid receptors on injury-induced microglial accumulation which may be mediated via NO.

Analgesics, Opioid↗
PubMedDate not supplied

The influence of agricultural and urban contamination on leech infestation of freshwater turtles, Phrynops geoffroanus, taken from two areas of the Uberabinha River.

Infestation by leeches on adult freshwater turtles Phrynops geoffroanus in two areas of the Uberabinha River, in Uberlândia, was investigated during the summer (January 2000). Fifty eight turtles were trapped: 26 (12 males, 14 females) in an agricultural area and 32 (16 males, 16 females) in an area with a more urban environment. The females present larger length and body mass (291.77+/-29.18 mm; 2233.30+/-511.40 g) than males (259.71+/-33.15 mm; 1488.68+/-529.35 g). Blood samples were drawn from the retrorbital sinus using heparinized micro-hematocrit capillary tubes, for microscopic and direct examination for intracellular parasites. Ectoparasitism by leeches, Placobdella bistriata, on young and adult animals was observed in the limb cavities of 28.1% of the urban area turtles. No leeches were found on the turtles in the agricultural area. Hemogregarine erythrocytic gametocytes were found in 15.4% of the agricultural area turtles, and in 37.5% of the urban area turtles. Concurrent parasitism by leeches and hemogregarines on the same individuals was seen on six turtles. Infections with microorganisms (bacteria and fungus) facilitated by the bites of leeches were not observed in another study on the same sample of infested turtles. However, 19% of the turtles collected in the agricultural area and 15% of the turtles from the urban area presented normocytic acute anemia. The occupation of the soil apparently interfered in the aquatic ecosystem favoring parasitism in the urban area.

Animals↗